Journal of Clinical Research

Background: Consent form completion errors may invalidate consent and waste participant and research time. The aim of this study was to compare error rates in an existing trial consent form with a revised version, developed through information design and user testing

Method: Study within a trial (SWAT) conducted within the ISDR trial of diabetic screening intervals. Using a sequential groups design, participants completed either the original trial consent form or a version that had been revised through iterative user testing and information design principles.

Results: Forms for 1,027 participants were analyzed: 307 revised forms and 720 original forms. Major error rates were low and similar in the two groups (1.0% in original forms; 0.6% in revised forms; p=0.61). Minor error rates were lower in revised forms (11.0% in original forms; 5.9% in revised forms; p=0.006), as were rates of any error (11.8% in original forms; 5.9% in revised forms; p=0.004).

Conclusion: Revising the consent form through user testing and graphic design resulted in a halving of error rates, although the effect requires further evaluation in a SWAT with random allocation.